Sanding machine

ABSTRACT

A sanding machine ( 1; 300 ) comprising a support structure ( 2; 302 ) for the piece ( 3 ) to be processed and a sanding unit ( 4 ) for the piece ( 3 ) itself. The sanding unit ( 4 ) comprises a frame ( 40 ) that supports a winding element ( 8 ) cooperating with kinematic means ( 9 ) suitable for setting it in motion according to a closed ring configuration on a plane (π 1 ) substantially parallel to the plane (π 2 ) defined by the support structure ( 2; 302 ) and a plurality of abrasive elements ( 10 ) combined with the winding element ( 8 ) spaced from one another and provided with an abrasive surface ( 16; 416 ) that comes in contact with the piece ( 3 ) during the movement of the winding element ( 8 ).

The invention concerns a sanding machine particularly suitable for beingused in the surface processing of panels, doors, furniture doors andsimilar parts.

This type of processing is generally carried out on raw or paintedwood-based materials, but in different applications it can be adoptedalso for different materials, like plastic or metal, to work on cornersor to remove the residues of previous processing.

For this purpose automated sanding machines are known, in whichappropriate abrasive elements with suitable grain are placed in contactwith the surface of the piece to be sanded.

The abrasive elements are generally constituted by abrasive paper stripsclosed to form a ring and rotating on a pair of pulleys.

A particular type of machines normally used for sanding low reliefsurfaces involves the use of abrasive brushes comprising a plurality ofabrasive tapes, usually interchangeable, applied to the outer surface ofa rotating roller.

During operation these brushes are placed in contact with the piece tobe sanded, which is set in motion by a conveyor belt on which it isfixed.

The adhesion of the piece to the conveyor belt is guaranteed by theaction of suitable pressing elements that press the piece, as well as bythe holding effect obtained by means of a suction unit positioned on thesurface of the conveyor belt.

The piece to be sanded is set in motion by the conveyor beltsubstantially in one direction only with respect to the abrasive brushesthat, being usually positioned over the conveyor belt, determine thesanding of one side only of the piece to be sanded, usually the visibleupper surface.

Obviously, to carry out a complete sanding of all the sides of thepiece, including the edges, it is necessary to carry out successiveprocessing steps, including coordinated movements of the abrasivebrushes along different axes, or the rotation of the piece so as toposition the sides to be sanded in contact with the brushes.

In different applications, to sand the lateral profiles of the piece themachine is provided with a further sanding unit, where the abrasivebrushes of the type described above are arranged vertically, so thatthey can be placed in contact with the side edge of the piece.

A first drawback of these techniques is represented by the fact that thecomplete sanding of the piece requires several processing cycles.

Another drawback of these techniques is constituted by the fact that thepressure exerted by the abrasive brushes during their rotation mayaffect the quality of the processing in small pieces, in fact it isdifficult for the pressing element to keep the piece adherent to theconveyor belt, due to the dimensions of the brushes themselves.

The aim of this invention is to overcome the drawbacks described above.

One of the main aims of the invention is to manufacture a sandingmachine with which a piece can be sanded with a single processing cycle.

Another aim of the invention is to manufacture a sanding machine that iscapable of sanding a piece ensuring a higher quality compared to theequivalent machines of the known types.

A further aim of the invention is to manufacture a sanding machinerequiring simplified maintenance operations compared to machines of theknown types. The aims described above have been achieved through theimplementation of a sanding machine that, according to the contents ofthe main claim, is of the type comprising a support structure for thepiece to be processed and a sanding unit for sanding said piece,characterized in that said sanding unit comprises a frame supporting:

-   -   at least one winding element cooperating with kinematic means        suitable for setting it in motion according to a closed-ring        configuration on a plane that is substantially parallel to the        plane defined by said support structure;    -   a plurality of abrasive elements combined with said winding        element, positioned spaced from one another and provided with at        least one abrasive surface suitable for coming in contact with        said piece during the movement of said winding element.

According to a favourite application of the invention, the windingelement is constituted by a closed belt wound between two pulleys, oneof which is motor driven.

Each abrasive element is constituted by a laminar abrasive elementconnected with the belt by means of a shaft positioned substantiallyperpendicular to the plane defined by the support structure.

To advantage, along their trajectory the abrasive elements sequentiallyinvolve the side edges of the piece and its visible upper surface, thuscarrying out the complete sanding of the piece.

The aims and advantages mentioned above will be better highlighted bythe description of some among many possible applications of theinvention in question, with reference to the enclosed drawings, wherein:

FIG. 1 is an axonometric view of the sanding machine object of theinvention;

FIG. 2 shows a partial cross-section of FIG. 1;

FIG. 3 is a side view of FIG. 1;

FIGS. from 4 to 6 are schematic top views of the machine object of theinvention in different piece processing phases;

FIG. 7 shows a cross-section of an enlarged detail of FIG. 1;

FIG. 8 is an axonometric view of a detail of an abrasive element;

FIG. 9 is an axonometric view of a detail of FIG. 7;

FIGS. from 10 to 12 show a schematic top view of a variant of themachine object of the invention in different piece processing phases;

FIG. 13 is a schematic top view of another variant of the invention;

FIG. 14 is an axonometric view with a partial cross section of a furthervariant of the invention;

FIG. 15 shows a variant of FIG. 9.

The sanding machine object of the invention is shown in FIG. 1, where itis indicated as a whole by 1.

It substantially comprises a support structure 2 for the piece 3 to beworked and a sanding unit, indicated as a whole by 4, for sanding thepiece 3.

In the application of FIG. 1 the support structure 2 is movable withrespect to the sanding unit 4 and substantially comprises a conveyorbelt 5 wound to form a closed ring between a pair of rotating cylinders6, 7.

In different applications the relative movement between the sanding unit4 and the support structure 2 can be obtained, for example, by movingthe sanding unit 4 only.

According to the invention, the sanding unit 4 comprises a frame 40supporting a winding element 8, as can be seen in greater detail in FIG.2, cooperating with kinematic means, indicated as a whole by 9, and aplurality of abrasive elements 10, combined with the winding element 8and arranged spaced from one another along the development of thewinding element 8 itself.

In particular, the winding element 8 assumes a closed ring configurationon a plane π1 substantially parallel to the plane π2 defined by thesupport structure 2.

For convenience's sake said planes π1 and π2 are positionedhorizontally, but it is clear that in different applications they canhave any position, even inclined. As to the winding element 8, it isconstituted by a belt closed to form a ring and cooperating, as alreadysaid, with the kinematic means 9 that set it rotating on plane π1.

The kinematic means 9 are constituted by two pulleys 11, 12, betweenwhich the winding element 8 is wound and by motorization means,indicated as a whole by 13, mechanically connected with one of saidpulleys, in the case represented in the figure with pulley 12, to set itrotating.

Each one of the abrasive elements 10, as shown in FIG. 7, is constitutedby a laminar abrasive element 14 connected with the winding element 8 bymeans of a shaft 15 arranged substantially perpendicular to the supportstructure 2, where the piece to be processed 3 is positioned.

The laminar abrasive element 14, as shown in the detail of FIG. 8, ispreferably constituted by abrasive strips of the known type, comprisinga piece of abrasive paper 16, on which a series of fringes is obtained.

The abrasive paper 16 is positioned at the side of a series of fibrouselement 17 that, owing to their intrinsic elasticity, determine theflexibility of the laminar abrasive element 14 itself.

As shown in the figures, and in particular in the top views of the FIGS.from 4 to 6, each laminar abrasive element 14 is positioned inclinedwith respect to the advance directions of the winding element 8,indicated by the arrows 18 and 19, with respect to the two main sides20, 21 on which the winding element 8 itself is wound.

This inclination, in fact, ensures the soft aggression of the corners ofthe piece 3 with which the laminar abrasive elements come in contact.

The laminar abrasive element 14 clearly has the abrasive paper 16positioned at the front and the fibrous elements 17 positioned at therear with respect to the advance directions of the winding element 8.

To allow each laminar abrasive element 14 to be arranged in an inclinedposition, the shaft 15 is provided with articulation means, indicated asa whole by 22, that make it possible to define, as we shall see lateron, suitable and different inclined positions of the laminar abrasiveelement 14.

The articulation means 22 can be carried out according to knowntechniques commonly used in the mechanical sector.

To facilitate maintenance operations and the replacement of the laminarabrasive elements 14, the same are advantageously joined to theirrespective support shaft 15 so that they can be removed, thus ensuringeasy and quick replacement.

This is highlighted in FIG. 9, where it can be observed that the laminarabrasive element 14 is removably constrained to the support shaft 15through holding means, indicated as a whole by 23, constituted by amovable plate 24 positioned against the laminar abrasive element 14through the operation of a pawl 25.

To facilitate the guided movement of the abrasive elements 10 on theframe 40 guide means are provided, indicated by 26 in FIG. 7,substantially constituted by rails that develop at least for part of thelength of the winding element 8 and slidingly receive the shaft 15 ofthe abrasive element 10.

In particular, the shaft 15 is combined with rolling sliding means 27that, cooperating with the rails 26, guide the abrasive elements 10,thus reducing the stress on the winding element 8 and reducing theoscillation of the winding element 8 to the minimum.

To advantage, said guide means 26 will develop for a width correspondingto the maximum width admissible for the pieces to be processed.

Combined with the sanding unit 4, as it can be observed in detail inFIG. 2, there are pressing elements, indicated as a whole by 28,constituted by rollers that during the sanding process are positioned insuch a way as to adhere to the piece to be processed 3 and facilitateits adhesion to the support structure 2.

Furthermore, the support structure 2 may be provided with suction means,not represented in the figure for simplicity's sake and in any casealready known, which further increase the adhesion of the piece 3.

During operation, as shown in FIGS. 4, 5, and 6, the piece to beprocessed 3 advances in a substantially perpendicular direction withrespect to the parallel advance directions 18, 19 of the winding element8.

When at the beginning of the cycle the piece 3 comes in contact with theabrasive elements 10, as shown in detail in FIG. 4, the laminar abrasiveelements 14 of the main side 21 come in contact with the front side edge3 a of the piece 3, thus sanding this edge.

Successively the piece 3 advances further and, as can be observed inFIG. 5, comes in contact with the abrasive elements 14 of both sides 20,21.

In particular, the abrasive elements 14 of the side 20 come in contactwith the side edge 3 b and the visible upper surface 3 e of the piece 3.

Analogously, the abrasive elements 14 of the side 21 come in contactwith the side edge 3 d and the same visible surface 3 e.

In the last sanding phase, as shown in FIG. 6, the abrasive elements 14of the main row 20 come in contact with the last side edge 3 c thathasn't been sanded yet, thus finishing the processing of the piece 3.

It is clear that, independently of the shape of the piece to be sanded,all its side edges, as well as its visible surface are sanded in asingle processing cycle.

It is also clear that during the processing phases the pressing elements28, not represented in the FIGS. from 4 to 6 for simplicity's sake, willbe advantageously rested on the upper surface 3 e of the piece 3, inorder to keep it adherent to the conveyor belt 5.

It is important to point out that, compared to the known types ofsanding machines, in this case the pressing elements 28 can be arrangedat a shorter distance from one another, thus ensuring optimal adhesionalso for small pieces.

In case of application to more sophisticated sanding machines, a sandingunit 4 of the type described above may also be advantageously combinedwith traditional sanding units, for example sanding units with rotarybrushes.

The FIGS. from 10 to 12 schematically show a variant of the sandingmachine object of the invention during different processing phases; itdiffers from the previous one for the different inclination of thelaminar abrasive elements 114.

Said abrasive elements, as it can be observed, are inclined according toan alternate configuration that, compared to the previous application,ensures compensated distribution of stresses on the winding element, dueto the contact of the laminar abrasive elements 114 with the piece to beprocessed.

In this way the oscillation of the winding element during its rotationcan be further reduced and the construction of the sanding machine maybe simplified, since there is no need for guide means combined with theshaft of each abrasive element.

FIG. 13 shows a further variant of the invention, which differs from theprevious applications described above for the different arrangement ofthe laminar abrasive elements 214 that, in this case, are perpendicularto the advance directions of the winding element.

FIG. 14 shows a further variant of the invention, indicated as a wholeby 300. It differs from the first practical application for thedifferent construction of the support structure 302, which in this caseis constituted by a plurality of rotating rollers 305 positioned side byside which, while rotating, bring with themselves the piece to beprocessed that rests upon them.

Finally, FIG. 15 shows a different construction of the holding means 423of the laminar abrasive element 414, comprising a movable plate 424positioned against the laminar abrasive element 414 owing to the actionof a pair of lateral springs 430 that are integral with the shaft 415.

In this case the laminar abrasive element 414 can advantageouslycomprise is two distinct parts 416, 417, the first part 416 beingconstituted by the abrasive paper and the second part 417 beingconstituted by fibrous elements.

With this configuration, maintenance operations may require thereplacement of the worn abrasive paper 416 only, with no need to replacealso the fibrous elements 417.

The above clearly shows that the sanding machine object of theinvention, in the different variants illustrated and described herein,achieves the aims set and offers the advantages described.

Upon implementation, further modifications that are not described andrepresented herein may be made on the machine object of the invention.

Said modifications may be constituted, for example, by a differentposition of the winding element, by a different execution of the same,for example with ring chains wound on gear wheels, or again by adifferent execution of the laminar abrasive elements and a differentmethod to apply them to the winding element itself.

These and other variants, not described and not represented herein, mustall be considered protected by this patent, provided that they areincluded in the innovative concepts expressed in the following claims.

1. The sanding machine comprising: a support structure for supportingthe piece to be processed and a frame supporting at least a sanding unitfor processing said piece, said sanding unit comprising a windingelement cooperating with kinematic means for moving it according to aclosed ring configuration, wherein said closed ring configuration ofsaid winding element belongs to a plane substantially parallel to theplane defined by said support structure and wherein said winding elementsupports a plurality of abrasive elements spaced from one another,disposed substantially perpendicular to the plane of said supportstructure and defining two parallel advance directions, said abrasiveelements comprising a laminar abrasive element connected with saidwinding element through a shaft substantially perpendicular to saidplane defined by said support structure, said abrasive element beinginclined with respect to the advance directions of said winding element.2. The sanding machine according to claim 1 wherein said kinematic meansof said winding element comprises at least two pulleys between whichsaid winding element is wound and motorization means cooperating with atleast one of said pulleys to set it rotating.
 3. The sanding machineaccording to claim 1 wherein said laminar abrasive element is removablyconnected with said shaft through holding means.
 4. The sanding machineaccording to claim 3 wherein said holding means comprise at least onemoving plate suitable for being placed against the laminar abrasiveelement through the operation of a pawl.
 5. The sanding machineaccording to claim 3 wherein said holding means comprise at least onemoving plate suitable for being placed against the laminar abrasiveelement through the action of at least one spring integral with saidshaft.
 6. The sanding machine according to claim 1 wherein said shaftcomprises articulation means suitable for defining said inclinedposition of said laminar abrasive element.
 7. The sanding machineaccording to claim 1 comprising guide means combined with said frame,suitable for slidingly receiving said shaft for at least one sectionduring its movement.
 8. The sanding machine according to claim 7 whereinsaid guide means comprise at least one track integral with said frameand are suitable for receiving rolling sliding means combined with saidshaft.
 9. The sanding machine according to claim 1 wherein said supportstructure can be moved with respect to said sanding unit.
 10. Thesanding machine according to claim 1 wherein said support structurecomprises a conveyor belt closed to form a ring between at least onepair of rotating cylinders.
 11. The sanding machine according to claim 1wherein said support structure comprises a plurality of rotating rollerspositioned side by side.
 12. The sanding machine according to claim 1wherein said sanding unit can be moved with respect to said supportstructure.
 13. The sanding machine according to claim 1 comprisingsuction means combined with said support structure and suitable forkeeping said piece adherent to said support structure.
 14. The sandingmachine according to claim 1 comprising one or more pressing elementscombined with said frame, suitable for being placed in contact with saidpiece to keep it adherent to said support structure.